Telegraph system



Dec. 26,1939. L E'RT w 2,184,836

TELEGRAPH SYSTEM Filed April 23, 1937. 2 Sheets-Sheet l Dec. 26, 1939. v R, HELMET 2,184,836

TELEGRAPH SYSTEM Filed April 23, 1937 2 Sheets-Sheet 2 Patented Dec. 26, 1939 STATES TELEGRAPH SYSTEM Robert Helmert, Berlin-Lankwitz, Germany, assignor to C. Lorenz Aktiengesellschaft, Berlin- Tempelhof, Germany, a company Application April 23, 1937, Serial No. 138,538

In Germany April 23, 1936 6 Claims. 01. 1782) similar to those used for the telegraph signals- It may occur in such systems that undesired connections are established in cases when telegraph signals are caused to influence the selector magnet due to interferences or irregular manipulations by the operators, whereby the selector is 10 brought into an undesired position.

In order to avoid this disadvantage, the present invention provides switching means which, in case that an anomalous train of impulses reaches a selector, prevent its testing into a line. In

such event a further feature of the invention comprises the release of all selectors previously set and also the disconnection of the telegraph apparatus allotted to the subscribers station.

An anomalous train of impulses exists either 20. when the number of pulses applied to the selector exceeds the maximum number of steps provided for its setting, or, in cases that hunting selectors are concerned, when subsequent to a finished train of impulses additional impulses arrive be- 25. fore the selector has tested. An excessive number of impulses may occur due to operation of the transmitting key during the period of selective dialing. The other type of anomalous impulse train may be explained more fully by briefly considering the operation of an impulse operated switch. In this type of switch a train of impulses serves to position a selector member, after which a pause of predetermined duration is necessary for the selector to test and complete the connection. Other series or trains of impulses then serve to make further connections as is well known in the art. If, then, a second train of impulses arrives before the selector has tested, the effect will be similar to an extension or an addition to the original impulse train and therefore will not give the desired indication.

The present invention will be more readily understood from the following description taken in conjunction with the accompanying drawings, in which:

Fig. 1 shows a wiring diagram of a subscribers station equipped with a printing telegraph apparatus; Fig, 2 shows the wiring diagram of a preselecting device; while Fig. 3 represents the circuit arrangement of a group selector equipment.

The relays are designated with capital letters and their pertaining contacts carry the corresponding designations in small letters which are primed when distinction therebetween is required. The contacts 7cm, in and 702 shown in Fig. 3 are closed in dependence upon vertical selector movements, the contact k0, however, is not closed before the 10th step. The contacts 1171 to w; are closed on a rotary motion of the selector. The contacts 2011 are closed by the selector on its 11th step which effects the release.

The printing telegraph a'pparatus according to Fig. 1 and the preselector device according to Fig. 2 are interconnected over the two lines a and I), while the last mentioned preselector device is connected to the group selector arrangement according to Fig. 3 over the lines a, b" and c". When the system is in a condition of rest, all contacts are in a position as illustrated in the Figs. 1, 2 and '3 Only one single subscribers station has been illustrated inthe present embodiment of the invention. The corresponding station is designed in exactly the same manner as the station shown in Fig. 1, while its allotted preselector and group selector arrangements correspond to those shown in the Figs. 2 and 3. The outgoing lines a", b", and 0" shown at the right side of Fig. 3 lead to the final selectors (not shown) which operate in a manner well known in connection with automatic telephony, from where they are extended to. the lines of the 00- operating station which correspond to the line (110, bio and (310 of Fig. 2.

When for the purpose of communication a connection is to be established from the printing telegraph apparatus in Fig. 1 to a corre.-'

m to the battery B. The right winding of relay E is continuously supplied, but the current now D of the preselector, interrupter U, battery to ground, so that the preselector starts its movement, whereby its wiper assemblies a, b, c and 11 test for a free group of lines a, b", c". As soon as the wipers have found a free group of lines, the relay T having windings T1, T2 and T3 is operated in a circuit established from ground over the contacts 1'2, ha, windings T1, T2 of relay T, wiper c, line of the free group of lines, contact k1 (Fig. 3), contacts 111, m, relay C, battery to ground. a The relay T has one highly resistive winding T1 which permits this relay to attract only in cases when no further preselector is connected with the c-wire which is to be tested, 1. e. when no potential drop exists across the relay C of the group selector. Relay C is provided with two windings C1 and C2.

The relay T reverses its contacts t1, ta, ta

and ii. The highly resistive winding T1 of the relay T is short circuited at the contact ta, so that a current of higher intensity now flows over the c-wire. As a result thereof an increased potential drop prevails at the C relay of the appertaining group selector, whereby further preselectors are prevented from testing into this group selector, which is simultaneously characterized as busy. The reversed contact 134 interrupts the circuit for the rotary magnet D of the preselector which is arrested in the postion to which it has been set. The contact t4 also establishes a circuit for the relay H from ground over the wiper d, contacts in, t4, relay I-I, battery to ground. The energizing circuit for the relay H is sustained over the contacts In and T1 to ground as soon as this relay has attracted. The contact ha disconnects the left winding of the relay T, but this is at first without any effect as the winding T2 of the relay T remains energized over the contacts T2 and lie. The circuit for the rotary magnet D which already has been interrupted by the reversed contact t; is broken again at the operated contact hz.

The reversed contact t2 connects the relay S with the battery in a circuit which is traced from ground, relay S, contact 112, wiper b, line 1), contact m (Fig. 3), and contact 1J4, battery to ground. Due to the fact that this battery applies a voltage to the relay S of opposite sense than that supplied thereto over the back contact f2 of relay T, the relay S reverses its contact s. The relay N is also influenced over the same circuit as the current flow through its right winding has been reversed. The two windings of this relay N are so dimensioned that the effect of the right winding predominates over that of the left winding. The contacts s, m and n2 now reversed accomplish current reversal over the subscribers loop which is supplied from the battery B and shown in Fig. 1. This reversed current fiow operates relay P which closes its contact 19' thus connecting the relay M to the main supply Ne. On its energization the relay M closes its contacts m2, m3 and mi and opens it contact 1121. The contacts m3 and mi connect the motor Mo of the printing telegraph apparatus to the main supply Ne with the result that the apparatus is started. The contact m1- removes the short circuit from the transmitter contact SK. The contact m2 together with the release key ST provides a shunt connection across the condenser C and the resistance Wi, so that the direct current of the subscribers loop now fiows over the transmitter contact SK and through the receiving magnet EM.

At first only the two winding relay C of the group selector (Fig. 3) is operated, whereby its contacts 01, c2 and 03 are reversed. The setting of the group selector during the dialling operation at the subscribers station is effected in a well known manner. As soon as the subscriber (Fig. 1) actuates his dial, the contact nsi is opened and closed in a rhythm which corresponds to the pulses sent out by the dial. For the purpose of protecting the printing telegraph receiver against interferences, the receiving magnet EM is simultaneously short circuited by the agency of the contact nsa. The current interruptions in the subscribers loop cause the relay E to operate, due to the fact that the current through the left winding of this relay decays at each interruption of the subscribers loop a, b, so that the current which continuously flows through the right winding of this relay again reverses the contact e. The movement of the contact e operates the two winding impulse relay I of the group selector (Fig. 3) over the line a", contacts 115,700, w1,-relay winding I1 and battery to ground, because the oscillating contact c intermittently applies battery potential in series with the battery potential at relay I or a battery potential which opposes the battery potential at the relay 1.

The contact 2'2 which is closed in rhythm with the pulses, when the impulse relay I is active, establishes a circuit for the magnet for vertical movement Hz. This current flows over the following path: ground, supervisory relay WK, contacts C2, 102, 2'2, vertical movement magnet H2, battery, ground. The three winding relay P is operated at the same time as the relay H2 over winding P1 connected in parallel therewith. Since this relay is equipped with a timing device it is not permitted to release as long as the successive pulses of an impulse train arrive. This relay P releases after the first train of impulses has been finished, and the succeeding incoming train of impulses energizes the rotary magnet D from ground over the relay WK, contacts 194 i1, 702, rotary magnet D and battery to ground, so that the group selector will be set to an idle connector (not shown) of the desired group. The further connection to the subscribers station is not illustrated since it is not a part of this invention and is well known to those skilled in the art.

If the teleprinter apparatus of the subscribers station instead of impulse trains corresponding to the rules of operation transmits an anomalous train of impulses, e. g. telegraph signals by an opening or closing of the transmitter contact SK, the impulse relay I (Fig. 3) is first caused to operate in the same manner as above described in connection with the transmission of dialling impulses. This relay in turn actuates the vertical motion magnet H in the energizing circuit above explained. Since the relay P remains attracted during the arrival of the successive pulses as previously stated, the contacts 131, p2 and p3 remain closed and the contact :04 remains open during this interval. As soon as the group selector has finished its th vertical step, the cam contact k0 is reversed. At the conclusion of the pulse which effected this 10th step, even the contact i4 opens, so that the energizing circuit for the relay I is interrupted, but at the same time a new circuit is established for three winding, slow release relay Y over the contacts s, 700, is, relay winding Y1, battery to ground. The succeeding pulse therefore causes the relay Y to attract, which opens its contact 713, thus interrupting the testing circuit for the relay P at winding P2 with the result that the selector is prevented from testing a line. Upon operation relay Y locks itself over winding Y2 by opening contact yz. Since the relay winding I1 is not again energized, the slow to release relay P releases, closing contact n4, whereupon the selector turns due to the energization of its rotary magnet D in a circuit which is traced from ground through relay WK, over contacts 194, ii, k2, rotary magnet D, battery toground. The attraction of the rotary magnet D causes its contact d to close, so as to establish a circuit for winding I2 of the relay I. This relay attracts and opens its contact i1, thereby recurrently interrupting the circuit for the rotary magnet D. The above described operation of this magnet advances the selector step by step, but the selector is unable to test for a free line since, as mentioned above, the circuit for the test windings P2 of relay P is interrupted at the contact 2/3. Rotary switch D opens contacts un, wz, ms and wr as soon as it operates, but does not operate um and 1012 unless it makes 11 steps.

The polarity of the current source which is connected to the wire b over the contact 112 is reversed by the reversed contact 1 /4 with the result that the relays S and N (Fig. 2) return their contacts into the positions illustrated in the drawings. The direction of current flow through the subscribers line a, b" is reversed as the result of the returned contacts 8, m and 712, so that the relay P (Fig. 1) again opens its contact 19' thus interrupting the current path for the relay M. The so returned contacts ms and mi open the circuit for the motor Mo of the printing apparatus which is stopped, while the contact m2 simultaneously interrupt-s the subscribers line. The relay E (Fig. 2) thereby returns its contact 6 into the position shown and short-circuits the relay R which releases after the elapse of a given period. The opened contact 7'1 effects the release of the relay I-I since the contact "as has already been opened. The release of the relay T and the release of the relay C of the group selector is acccomplished, when the contact T2 is restored to normal. Also the re lay Y of the group selector releases owing to the interrupted loop in consequence of the returned contacts t1 and 1 2. This relay is thereby restored to the condition of rest. The selector is.

horned in a manner well known in the technics. The entire system is now restored to a condition of rest before an undesired connection is built up as the result of telegraph signals from the printing telegraph apparatus influencing the selector. The stopped printing telegraph apparatus indicates to the subscriber that a regular connection has not been established. The subscriber may now establish a correct connection by the agency of his dial.

If an anomalous train of impulses follows after the proper operation of the vertical selector Hz the rotary selector D operates in a similar manner to that described above except that it causes the rotation at a different level corresponding 1 to that selected instead of on the tenth level "as described above. Upon its eleventh step rotary switch D closes contact wu impressing reverse current on line b" and causing release of the apparatus as described above. Closing of contact wm serves to impress reverse polarity on line c" and effect release of other mechanism.

What is claimed is:

l. A telegraph system comprising telegraph sets, lines and selectors for interconnecting said sets, means for impressing a normal series of current impulses on one of said lines for operating said selectors for testing to select an idle line for establishing a circuit between said sets for intercommunication, and switching means responsive to an anomalous series of current impulses impressed on said line for disabling said selectors from testing.

2. A telegraph system according to claim 1, further comprising means controlled by said switching means for causing release of said telegraph sets from said connection.

3. A telegraph system according to claim 1, in which said switching means comprises a relay operated in response to a series of current impulses exceeding normal.

4. A telegraph system according to claim 1, in which said switching means comprises a relay, means responsive to the highest normal step of one of said selectors for preparing an operating circuit for said relay, and means for closing the circuit of said relay in response to an additional current impulse.

5. A telegraph system comprising telegraph sets, lines and selectors for interconnecting said sets, said selectors being operated in steps for making suitable selections, means for successively impressing a series of impulses below a predetermined maximum number on said lines for operating said selectors for establishing a circuit between said sets for communication purposes, and means responsive to a series of current impulses above said maximum number for disabling said selectors from completing a connection.

6. A telegraph system according to claim 5, in which said selectors operate by testing for establishing said circuit, and in which said disabling means comprises a relay operated in response to advance of said selectors beyond a predetermined maximum position for opening said testing circult.

ROBERT HELMERT. 

